The technology generally relates to determining a status of an optical channel between two components. For example, the components may be connected via an optical link including a plurality of optical channels. A first portion of the optical channels may be in use such that a second portion of the optical channels may be redundant channels. The component may include a test generator that transmits and receives a data pattern over each channel. The test generator may determine, based on the received data pattern, a status of each of the channels. If the status of a given channel is a failure status, the component may divert data for the given channel to a redundant channel.

An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at two phase-locked modulation frequencies F.sub.1 and F.sub.2. COR performance parameters are determined by comparing two frequency components of the COR output. The group delay variation (GDV) information is obtained by comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two modulation frequencies shifted by the optical frequency offset f.

Methods and assemblies for determining a property or environment of an optical fiber, including: measuring a frequency dependent electrostrictive response of an optical fiber; and based on the measured frequency dependent electrostrictive response, determining a property of the optical fiber. The property or environment of the optical fiber includes one or more of optical fiber type, optical fiber material type, optical fiber material property, optical fiber area, optical fiber geometry, optical fiber condition, optical fiber stress and strain, optical fiber environment, optical fiber temperature, optical fiber routing, optical fiber spooling, and optical fiber radiation exposure.

Characterizing a first OLTS includes connecting a first test cable directly to a second power meter of the first OLTS, connecting the first test cable to a second test cable, and connecting the second test cable directly to a connection port of a second OLTS. The method also includes determining a first characterization power of the first OLTS by measuring an optical power of light transmitted from a light source of the second OLTS with the second power meter of the first OLTS. The method further includes disconnecting a first test cable from the second power meter of the first OLTS, connecting the first test cable directly to a connection port of the first OLTS, and determining a second characterization power of the first OLTS by measuring an optical power of light transmitted from the light source of the second OLTS with the first power meter of the first OLTS.

An example system includes circuitry to receive an input signal, to provide a related signal based on informational content of the input signal, and to obtain parametric data associated with the input signal. The parametric data represents one or more signal characteristics other than the informational content. The example system also includes a first switch that is configurable to provide first data based on the related signal to one or more first channels of the system; and a second switch that is configurable to provide second data based on the parametric data to one or more second channels of the system.

A method of automated testing and evaluation of a node of a communications network, the method comprising: a management computer interacting with the node to discover fiber trails within the node that can be safely tested; and the management computer interacting with the node to test at least continuity of each identified fiber trail that can be safely tested.

Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, S, based on the measured EMB at a first reference measurement wavelength, M. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at two phase-locked modulation frequencies F.sub.1 and F.sub.2. COR performance parameters are determined by comparing two frequency components of the COR output. The group delay variation (GDV) information is obtained by comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two modulation frequencies shifted by the optical frequency offset f.

Techniques are disclosed for aligning an optical transmitter with an optical receiver for a line-of-sight communications link, wherein the optical transmitter comprises a laser array emitter, the laser array emitter comprising a plurality of laser emitting regions, wherein each of a plurality of the laser emitting regions is configured to emit laser light in a different direction such that the laser array emitter is capable of emitting laser light in a plurality of different directions. The system can run produce emissions from different laser emitting regions until a laser emitting region that is in alignment with the optical receiver is found. This aligned laser emitting region can then be selected for use to optically communicate data from the optical transmitter to the optical receiver.

An optical module includes an optical amplifier configured to amplify Wavelength Division Multiplexing (WDM) channels transmitted on a fiber; and an optical time domain reflectometer (OTDR) configured to transmit an OTDR signal on the fiber and detect a back-scattered signal based thereon to test the fiber, wherein a wavelength of the OTDR signal is one of i) between one or more wavelengths associated with the optical amplifier and one or more wavelengths associated with the WDM channels and ii) greater than the one or more wavelengths associated with the WDM channels, for in-service operation of the OTDR.